Evaluation of Rebar Corrosion in Concrete by Active Thermal Sensing

摘要

Active thermal (infrared) sensing has been used to locate simulated areas of corrosion in uncoated rebar test specimens embedded in concrete slabs. Varying amounts of rebar corrosion were simulated experimentally by milling notches into steel bars and then filling the notches with an iron oxide paste. The rebars were embedded in concrete and then resistively heated using DC current. Images of the heated rebars (in concrete) were acquired using an infrared focal plane array camera. Infrared images, illustrating the ability to detect non-destructively a reduction in rebar cross-sectional area of only 10 percent, are presented. In addition, results are presented demonstrating the dependence of the resulting thermal images on the orientation of the defect.